content: /**
   * Copyright (c) 2016-present, RxJava Contributors.
   *
   * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in
   * compliance with the License. You may obtain a copy of the License at
   *
   * http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software distributed under the License is
   * distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See
   * the License for the specific language governing permissions and limitations under the License.
   */
  
  package io.reactivex.flowable.internal.operators;
  
  import java.util.Iterator;
  import java.util.concurrent.Callable;
  import java.util.concurrent.atomic.*;
  
  import org.reactivestreams.*;
  
  import hu.akarnokd.reactivestreams.extensions.*;
  import io.reactivex.common.RxJavaCommonPlugins;
  import io.reactivex.common.annotations.Nullable;
  import io.reactivex.common.exceptions.*;
  import io.reactivex.common.functions.Function;
  import io.reactivex.common.internal.functions.ObjectHelper;
  import io.reactivex.common.internal.utils.ExceptionHelper;
  import io.reactivex.flowable.Flowable;
  import io.reactivex.flowable.internal.queues.SpscArrayQueue;
  import io.reactivex.flowable.internal.subscriptions.*;
  import io.reactivex.flowable.internal.utils.BackpressureHelper;
  
  public final class FlowableFlattenIterable<T, R> extends AbstractFlowableWithUpstream<T, R> {
  
      final Function<? super T, ? extends Iterable<? extends R>> mapper;
  
      final int prefetch;
  
      public FlowableFlattenIterable(Flowable<T> source,
              Function<? super T, ? extends Iterable<? extends R>> mapper, int prefetch) {
          super(source);
          this.mapper = mapper;
          this.prefetch = prefetch;
      }
  
      @SuppressWarnings("unchecked")
      @Override
      public void subscribeActual(Subscriber<? super R> s) {
          if (source instanceof Callable) {
              T v;
  
              try {
                  v = ((Callable<T>)source).call();
              } catch (Throwable ex) {
                  Exceptions.throwIfFatal(ex);
                  EmptySubscription.error(ex, s);
                  return;
              }
  
              if (v == null) {
                  EmptySubscription.complete(s);
                  return;
              }
  
              Iterator<? extends R> it;
  
              try {
                  Iterable<? extends R> iterable = mapper.apply(v);
  
                  it = iterable.iterator();
              } catch (Throwable ex) {
                  Exceptions.throwIfFatal(ex);
                  EmptySubscription.error(ex, s);
                  return;
              }
  
              FlowableFromIterable.subscribe(s, it);
  
              return;
          }
          source.subscribe(new FlattenIterableSubscriber<T, R>(s, mapper, prefetch));
      }
  
      static final class FlattenIterableSubscriber<T, R>
      extends BasicIntFusedQueueSubscription<R>
      implements RelaxedSubscriber<T> {
  
  
          private static final long serialVersionUID = -3096000382929934955L;
  
          final Subscriber<? super R> actual;
  
          final Function<? super T, ? extends Iterable<? extends R>> mapper;
  
          final int prefetch;
  
          final int limit;
  
          final AtomicLong requested;
  
          Subscription s;
  
          FusedQueue<T> queue;
  
          volatile boolean done;
  
          volatile boolean cancelled;
  
          final AtomicReference<Throwable> error;
  
          Iterator<? extends R> current;
  
          int consumed;
  
          int fusionMode;
  
          FlattenIterableSubscriber(Subscriber<? super R> actual,
                  Function<? super T, ? extends Iterable<? extends R>> mapper, int prefetch) {
              this.actual = actual;
              this.mapper = mapper;
              this.prefetch = prefetch;
              this.limit = prefetch - (prefetch >> 2);
              this.error = new AtomicReference<Throwable>();
              this.requested = new AtomicLong();
          }
  
          @Override
          public void onSubscribe(Subscription s) {
              if (SubscriptionHelper.validate(this.s, s)) {
                  this.s = s;
  
                  if (s instanceof FusedQueueSubscription) {
                      @SuppressWarnings("unchecked")
                      FusedQueueSubscription<T> qs = (FusedQueueSubscription<T>) s;
  
                      int m = qs.requestFusion(ANY);
  
                      if (m == SYNC) {
                          fusionMode = m;
                          this.queue = qs;
                          done = true;
  
                          actual.onSubscribe(this);
  
                          return;
                      }
                      if (m == ASYNC) {
                          fusionMode = m;
                          this.queue = qs;
  
                          actual.onSubscribe(this);
  
                          s.request(prefetch);
                          return;
                      }
                  }
  
                  queue = new SpscArrayQueue<T>(prefetch);
  
                  actual.onSubscribe(this);
  
                  s.request(prefetch);
              }
          }
  
          @Override
          public void onNext(T t) {
              if (done) {
                  return;
              }
              if (fusionMode == NONE && !queue.offer(t)) {
                  onError(new MissingBackpressureException("Queue is full?!"));
                  return;
              }
              drain();
          }
  
          @Override
          public void onError(Throwable t) {
              if (!done && ExceptionHelper.addThrowable(error, t)) {
                  done = true;
                  drain();
              } else {
                  RxJavaCommonPlugins.onError(t);
              }
          }
  
          @Override
          public void onComplete() {
              if (done) {
                  return;
              }
              done = true;
              drain();
          }
  
          @Override
          public void request(long n) {
              if (SubscriptionHelper.validate(n)) {
                  BackpressureHelper.add(requested, n);
                  drain();
              }
          }
  
          @Override
          public void cancel() {
              if (!cancelled) {
                  cancelled = true;
  
                  s.cancel();
  
                  if (getAndIncrement() == 0) {
                      queue.clear();
                  }
              }
          }
  
          void drain() {
              if (getAndIncrement() != 0) {
                  return;
              }
  
              final Subscriber<? super R> a = actual;
              final FusedQueue<T> q = queue;
              final boolean replenish = fusionMode != SYNC;
  
              int missed = 1;
  
              Iterator<? extends R> it = current;
  
              for (;;) {
  
                  if (it == null) {
  
                      boolean d = done;
  
                      T t;
  
                      try {
                          t = q.poll();
                      } catch (Throwable ex) {
                          Exceptions.throwIfFatal(ex);
                          s.cancel();
                          ExceptionHelper.addThrowable(error, ex);
                          ex = ExceptionHelper.terminate(error);
  
                          current = null;
                          q.clear();
  
                          a.onError(ex);
                          return;
                      }
  
                      boolean empty = t == null;
  
                      if (checkTerminated(d, empty, a, q)) {
                          return;
                      }
  
                      if (t != null) {
                          Iterable<? extends R> iterable;
  
                          boolean b;
  
                          try {
                              iterable = mapper.apply(t);
  
                              it = iterable.iterator();
  
                              b = it.hasNext();
                          } catch (Throwable ex) {
                              Exceptions.throwIfFatal(ex);
                              s.cancel();
                              ExceptionHelper.addThrowable(error, ex);
                              ex = ExceptionHelper.terminate(error);
                              a.onError(ex);
                              return;
                          }
  
                          if (!b) {
                              it = null;
                              consumedOne(replenish);
                              continue;
                          }
  
                          current = it;
                      }
                  }
  
                  if (it != null) {
                      long r = requested.get();
                      long e = 0L;
  
                      while (e != r) {
                          if (checkTerminated(done, false, a, q)) {
                              return;
                          }
  
                          R v;
  
                          try {
                              v = ObjectHelper.requireNonNull(it.next(), "The iterator returned a null value");
                          } catch (Throwable ex) {
                              Exceptions.throwIfFatal(ex);
                              current = null;
                              s.cancel();
                              ExceptionHelper.addThrowable(error, ex);
                              ex = ExceptionHelper.terminate(error);
                              a.onError(ex);
                              return;
                          }
  
                          a.onNext(v);
  
                          if (checkTerminated(done, false, a, q)) {
                              return;
                          }
  
                          e++;
  
                          boolean b;
  
                          try {
                              b = it.hasNext();
                          } catch (Throwable ex) {
                              Exceptions.throwIfFatal(ex);
                              current = null;
                              s.cancel();
                              ExceptionHelper.addThrowable(error, ex);
                              ex = ExceptionHelper.terminate(error);
                              a.onError(ex);
                              return;
                          }
  
                          if (!b) {
                              consumedOne(replenish);
                              it = null;
                              current = null;
                              break;
                          }
                      }
  
                      if (e == r) {
                          boolean d = done;
                          boolean empty = q.isEmpty() && it == null;
  
                          if (checkTerminated(d, empty, a, q)) {
                              return;
                          }
                      }
  
                      if (e != 0L) {
                          if (r != Long.MAX_VALUE) {
                              requested.addAndGet(-e);
                          }
                      }
  
                      if (it == null) {
                          continue;
                      }
                  }
  
                  missed = addAndGet(-missed);
                  if (missed == 0) {
                      break;
                  }
              }
          }
  
          void consumedOne(boolean enabled) {
              if (enabled) {
                  int c = consumed + 1;
                  if (c == limit) {
                      consumed = 0;
                      s.request(c);
                  } else {
                      consumed = c;
                  }
              }
          }
  
          boolean checkTerminated(boolean d, boolean empty, Subscriber<?> a, FusedQueue<?> q) {
              if (cancelled) {
                  current = null;
                  q.clear();
                  return true;
              }
              if (d) {
                  Throwable ex = error.get();
                  if (ex != null) {
                      ex = ExceptionHelper.terminate(error);
  
                      current = null;
                      q.clear();
  
                      a.onError(ex);
                      return true;
                  } else if (empty) {
                      a.onComplete();
                      return true;
                  }
              }
              return false;
          }
  
          @Override
          public void clear() {
              current = null;
              queue.clear();
          }
  
          @Override
          public boolean isEmpty() {
              Iterator<? extends R> it = current;
              if (it == null) {
                  return queue.isEmpty();
              }
              return !it.hasNext();
          }
  
          @Nullable
          @Override
          public R poll() throws Throwable {
              Iterator<? extends R> it = current;
              for (;;) {
                  if (it == null) {
                      T v = queue.poll();
                      if (v == null) {
                          return null;
                      }
  
                      it = mapper.apply(v).iterator();
  
                      if (!it.hasNext()) {
                          it = null;
                          continue;
                      }
                      current = it;
                  }
  
                  R r = ObjectHelper.requireNonNull(it.next(), "The iterator returned a null value");
  
                  if (!it.hasNext()) {
                      current = null;
                  }
  
                  return r;
              }
          }
  
          @Override
          public int requestFusion(int requestedMode) {
              if ((requestedMode & SYNC) != 0 && fusionMode == SYNC) {
                  return SYNC;
              }
              return NONE;
          }
      }
  }
  